Molecularly Engineered Contorted Polyimides: Unraveling the Role of Backbone Rigidity in Gas Separation

Hong-Qin Zhao; Bing-Yu Zou; Bing-Xi He; Wei-Feng Peng; Lu-Hao Qiu; Feng Bao; Ming-Jun Huang; Huan-Yu Lei

doi:10.1007/s10118-025-3530-4

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Molecularly Engineered Contorted Polyimides: Unraveling the Role of Backbone Rigidity in Gas Separation

RESEARCH ARTICLE | Updated：2026-02-13

- Molecularly Engineered Contorted Polyimides: Unraveling the Role of Backbone Rigidity in Gas Separation
- Chinese Journal of Polymer Science Vol. 44, Issue 3, Pages: 733-742(2026)
- Affiliations：
  
  a.School of Emergent Soft Matter, State Key Laboratory of Advanced Papermaking and Paper-based Materials, South China University of Technology, Guangzhou 510640, China
  b.Suzhou Key Laboratory of Macromolecular Design and Precision Synthesis, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China
  c.Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, Guangdong Basic Research Center of Excellence for Energy and Information Polymer Materials, South China University of Technology, Guangzhou 510640, China
  d.State Key Laboratory of Green and Efficient Development of Phosphorus Resources, Guiyang 550014, China
- Author bio：
  
  huangmj25@scut.edu.cn (M.J.H.)
  leihy@suda.edu.cn (H.Y.L.)
- Funds：
- DOI：10.1007/s10118-025-3530-4
  CLC：
- Received：13 October 2025，
  
  Accepted：09 December 2025，
  
  Online First：02 February 2026，
  
  Published：15 March 2026
- Accepted：
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Zhao, H. Q.; Zou, B. Y.; He, B. X.; Peng, W. F.; Qiu, L. H.; Bao, F.; Huang, M. J.; Lei, H. Y. Molecularly engineered contorted polyimides: unraveling the role of backbone rigidity in gas separation. Chinese J. Polym. Sci. 2026, 44, 733–742

Hong-Qin Zhao, Bing-Yu Zou, Bing-Xi He, et al. Molecularly Engineered Contorted Polyimides: Unraveling the Role of Backbone Rigidity in Gas Separation[J]. Chinese Journal of Polymer Science, 2026, 44(3): 733-742.
Zhao, H. Q.; Zou, B. Y.; He, B. X.; Peng, W. F.; Qiu, L. H.; Bao, F.; Huang, M. J.; Lei, H. Y. Molecularly engineered contorted polyimides: unraveling the role of backbone rigidity in gas separation. Chinese J. Polym. Sci. 2026, 44, 733–742 DOI： 10.1007/s10118-025-3530-4.

Hong-Qin Zhao, Bing-Yu Zou, Bing-Xi He, et al. Molecularly Engineered Contorted Polyimides: Unraveling the Role of Backbone Rigidity in Gas Separation[J]. Chinese Journal of Polymer Science, 2026, 44(3): 733-742. DOI： 10.1007/s10118-025-3530-4.

摘要

Rigid dianhydride–contorted diamine microporous polyimides (PIM-PIs) generate high microporosity and sub-5 Å pores

enabling polyimide membranes with high CO

permeability and selectivity.

Abstract

Microporous polyimides (PIM-PIs) have emerged as promising high-performance membranes for gas separation. However

achieving an optimal balance between permeability and selectivity remains a major challenge. In this study

we designed and synthesized a series of PIM-PIs by combining rigid dianhydrides 9-bis(trifluoromethyl)-2

7-xanthenetetracarboxylic dianhydride (6FCDA) and 4

4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) with contorted diamines

including 9

9-bis(4-aminophenyl)fluorene (FDA)

9′-spirobifluorene-2

2′-diamine (SBFDA)

and 3

3′

3′-tetramethyl-1

1′-spirobiindane-5

5′-diamine-6

6′-diol (TSDA)

to systematically elucidate the relationship between hierarchical microstructure and gas transport behavior. Comprehensive characterization revealed that the 6FCDA-based polymers exhibited a higher microporosity (

micro

total

up to 54.7%) and fractional free volume compared to their 6FDA counterparts. Gas permeation measurements showed that the 6FCDA/SBFDA membrane delivered a CO

permeability of 386 Barrer and CO

/CH

selectivity of 30.2

exceeding the 2008 Robeson upper bound. Structure-property correlation analyses indicated that diffusion selectivity predominantly governed gas separation performance

with rigid

spirocyclic architectures suppressing chain packing to generate sub-5 Å micropores

as further validated by molecular simulations. The optimized 6FCDA/FDA membrane achieved a BET surface area of 423 m

·g

–1

while maintaining excellent mechanical strength and high thermal stability. This work establishes an effective monomer design strategy to overcome the permeability-selectivity trade-off through backbone rigidification

thereby advancing PIM-PIs for practical applications in natural gas purification and carbon capture.

关键词

Keywords

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